The proposal deals with two general research areas using reaction time tasks: facilitation and interference produced by noise stimuli in a visual display, and the effects of redundant signals in divided attention tasks. In letter identification tasks, the manipulation the kinds of noise stimuli is intended to investigate the nature of stimulus coding. In word categorization tasks, the presence of noise words is used to examine the temporal aspects of automatic sematic processing. The stimulus onset asychrony of target and noise will be a major experimental variable in all of the research on context effects. With divided attention tasks, we are attempting to determine when a redundant signals advantage does and does not occur, and to determine the nature of the combination rule in positive instances. Experimental variables include the number of redundant stimuli and the presence and absence of noise stimuli. The redundant signals effect will also be studied in a biomodal detection task. We are attempting to investigate the temporal dynamics of all of these processes, both by the use of measures of mean RT, and by the application of scaling procedures to the entire RT distributions.